A large component of municipal refuse, for instance, may comprise paper products, such as newspaper, cardboard in both flat and carton form, and the like. However, there is also and often in varying proportions, material such as waste metal particles and metal articles, both magnetic and non-magnetic, food waste, dirt or soil and articles or particles of glass and other materials. Due to the variation in the amount of the various types of material, often depending upon the area in which the refuse has been collected, it is quite difficult to find adequate separating devices, since those which may be highly effective are particularly adapted for and therefore essentially limited to the separation of smaller or larger fractions only. Since heavier materials are often intermixed with lighter materials, either or both of which may also vary considerably in size, conventional disc screens and so-called "wobbler" separators having spiral ribs on parallel shafts have been found to be unsuitable for the effective separation of refuse into both light and heavy components, as well as different sizes. Thus, heavier components tend to become intermized with large articles, such as newspapers or cartons, and thereby tend to be carried over the holes through which they are intended to drop. Such equipment is also quite heavy, with relatively heavy drives and substantial inertia, requiring considerable horsepower to start up in the event of jamming of material between moving parts or complete stoppage and hand cleaning operation. Also, trommel screens, to be effective, must be equipped with large screening surfaces and openings of four inches or more in diameter, which results in an unduly large proportion of light fractions passing through, thereby substantially reducing the yield of the light fractions.
Erickson U.S. Pat. No. 2,743,813 discloses a device for separating oversized particles from mine run ores having a series of horizontally disposed, parallel shafts which are hollow and have an elliptical configuration. Each shaft is provided with a series of transverse ribs which follow the transverse contour of the shaft, while the alternate shafts are placed at positions 90.degree. apart from the remaining shafts. The ribs of all of the shafts are in longitudinal alignment, the function of the ribs being primarily to guide the material moved by the rotating shafts. Johlige U.S. Pat. No. 1,941,147 discloses a classifying apparatus for ore, coal, stones and the like which includes a series of horizontally disposed, square, parallel shafts with different types of discs in lateral sets. These discs include spaced, circular discs mounted in different off-center positions on the same shaft, but in corresponding positions on all shafts. In one modification, elliptical discs are mounted centrally on the shafts, with alternate elliptical discs mounted at 90.degree. to the remainder. In another modification, all of the discs are three-sided, with each side being an arc, and are mounted at 60.degree. apart on each shaft. All of the discs on the respective shafts are in longitudinal alignment with each other. Conway U.S. Pat. No. 3,028,957 discloses an ore separator having a parallel series of hollow, elliptical rollers with a 90.degree. angular relationship between adjacent rollers and equally spaced elliptical ribs mounted on each roller, with all of the ribs in longitudinal alignment.
Among the objects of the present invention are to provide a separator which will handle a relatively large variety of different material, particularly when intermixed; to provide such a separator which will handle such intermixture of materials which may vary in the proportion of the sizes, as well as lighter or heavier materials; to provide such a separator which will separate the heavy fraction with a minimum of loss and secure the highest possible yield of light fractions; to provide such a separator which is particularly adapted to handle refuse; to provide such a separator which may be stopped and restarted with a minimum of horsepower; to provide such a separator which need not be unloaded in order to restart or eliminate a jam caused by a piece of refuse becoming jammed between two moving parts; to provide such a separator, the drive of which may be reversed in direction, in order to eliminate a jam; to provide such a separator which is adapted to handle relatively large load variations; to provide such a separator which is relatively simple in construction and economical to build; and to provide such a separator which is efficient and effective in use.